Process of controlling rate of oxidation



Sept. 25, 1928,.

1,685,520 H. R. cARVETH PROCESS OF CONTROLLING RATE OF OXIDATION Filed Jan. 29, 1926 N I l i I I I llll H I} IN IL! 51' I idi! 3 w in five Patented Sept. 25, 1928.

UNITED STATES PORATION OF NEW YORK. I

YORK, nssrenon :ro THE NEW YORK, n. 1., A con- ]?ROOESS OF CONTROLLING RATE E OXIDATION.

Application filed January 29, 1926, Serial This invention relates. to the reaction of metallic sodium with elementary oxygen for the formation of a solid product consisting substantially of sodium monoxide.

6 One object of the invention is to produce a finely divided sodium monoxide that is sufficiently porous to be chemically reactive with gases, particularly gaseous oxygen in reactions for production of sodium peroxide.

10 Another object of the invention is to produce sodium monoxide that is sufficiently uniform in quality to permit of its being marketed as a primary product. Another object of the invention is to make possible a reduction of 1 labor and other costs that enter into the final cost of sodium monoxide as'a primary or an intermediate product.

Before my invention there were two principal ways of making sodium monoxide,

2 neither one of which was satisfactory as is evidenced by the fact that the product has not hitherto been quoted or marketed. The first method was to expose metallic sodium in shallow layers about one half inch deep to air at temperatures of about 200 C. When the reaction begins acrust of sodium monoxide forms on the molten surface. This crust draws molten metal by capillary action to the surface and therefore into con- :0 tact with more air which makes further oxidation possible. However, the capillary action is incomplete and eventually it becomes ineflective before all of the metal is oxidized. The upper surfaces of monox- 5 ide are oxidized to sodium peroxide, after which no further reaction occurs excepting over time intervals too long for manufacturing purposes. The product therefore consists substantially of three more or less in- J termixed layers with sodium below, sodium peroxide above, and monoxide in between. This product is disagreeable and even dangerous to handle. When it is being used for the commercial production of either sodium 5 monoxide or sodium peroxide, further handling is necessary, which unavoidably introduces impurities into the final product.

The second method was to react metallic sodium with sodium peroxide. This reaction proceeds vigorously when once started,-too vigorously in fact to be easily controlled. It produces a product that has been fused during the course of manufacture and it is apt to enclose small globules of sodium;

No. 84,543, and in Germany June 6, 1825.

The high temperature developed tends to increase corrosion of containing vessels and thereby to detract from the purity of the product. The product is dense but lacking in orosity; even when finely ground it is di cult if not impossible to oxidize completely to sodium peroxide.

Sodium peroxide is one of theimportant products made from monoxide. It is, therefore, of great importance to have a process for making monoxide of such quality that it can be converted into a high grade of peroxide. Commercial peroxide should be dense, finely ground, exceptionally pure and of high test. The best way to make such peroxide is to oxidize finely divided monoxide of high purity, that is dense but also porous.

In my application #623,901 filed March 9, 1923. subject Process of conducting and controlling chemical reactions, I disclosed the general principle of using a solid reaction product as a carrier for liquid that is being reacted upon by a gas. This rinciple permits use of greatly extended 'sur aces and extremely thin layers of the liquid product upon which the gas is reacting. I have discovered that a surprisingly large amount of metallic sodium, in fact as high as 10% can be absorbed in and diffused by sodium monoxide and that such a mixture does not become pasty but retains all the characteristics of a dry powder. This mixture when oxidized properly furnishes a very superior quality of sodium monoxide.

As stated above I use finely divided soas a carrying medium;

dlum monoxide to this I introduce metallic sodium so that it will never be in excess of 10% by weight of the total mixture. I prefer a mixture of 10% or less. There is no diiliculty in completely oxidizing all of the sodium in the mass and the composition may be allowed to fluctuate between the upper limits of from 5% to 10% sodium down to 0% sodium as the lower limit.

Ordinarily I use air as-a soure of oxygen.

his is introduced into the reaction vessel in such a manner that the oxygen concentration in the reaction vessel is never over a few per cent, preferably Well below 10%. B restricting the input of air, I can control the rate of oxidation so that the reaction mass will never become either generally or locally overheated. The temperature "should not be permitted to rise above 250 C. It is 1mportantthat overheating be avoided because overheating gives undesirable physlcal characteristics to the product of reaction and tends to increase the corrosion of the reacting vessel.

In the accompanying drawing is shown an apparatus for oxidizing sodium to sodium monoxide by my process. One is a revolving retort, made of-iron, supported at the ends by bearings 2 and revolved by any suitable means. Air is introduced through 3, and escaping gases pass through 4:. A body of pulverulent sodium monoxide. 5, is held in the apparatus. Sodium may be introduced intermittently through 6, and when product 1s removed, 6 serves as an outlet opening when on the under side.

I wish it to be understood that any suit-- able means of stirring the pulverulent mass may be employed; also any suitable vessel that provides agitation; any means of maintaining a porous mass wherein sodium may be distributed uniformly and oxygen be permitted to come into contact with all parts of the pulverulent mass, come within the scope of my invention.

Sodium may be added continuously and the-product removed continuously if equip-v ment is designed for the purpose, but the process is unaltered by any such changes or modifications. The sodium may be added as liquid or as solid. The heat-of reaction is suflicient to melt the solid metal.

When the process is once started, rovision is made for unrestricted air radiation. The temperature should not be permitted to rise much above the temperature at which the reaction proceeds smoothly. In the apparatus shown the process is continuous excepting short interruptions when sodium is being introduced or product removed. Heating is unnecessary exceptin when the process is first started, and ana ytical control is unnecessary for successful operation, since there is a distinctive color change when the metallic sodium content of the mass approaches 0%.

What I claim is:

1. The purpose of producing sodium monoxide which consists in absorblng molten sodium in an excess of pulverized sodium monoxide at a reacting temperature and supplying oxygen.

2. he process of producing sodium monoxide which consists in absorbing molten sodium in an excess of pulverized sodium monoxide at a reacting temperature and supplying oxygen at such a rate as to maintain a substantially constant reacting temperature below the vaporization point of sodium. I

3. The process of producing sodium monoxide consisting in mixing metallic sodium dium in an atmosphere of nitro 11 contain-( '0 ing oxygen until all of the so ium is oxidized. I 7

6. The process of producin sodium monoxide consisting in mixin 4 so ium and finely divided sodium monoxide in pro ortions that do not produce a pasty mass, olding at a temperature between the melting (point of sodium and 250 0., agitating and a din ox gen. The process of producing sodium monoxide consisting in mixing sodium and finely divided sodium monoxlde in proportions that do not produce a pasty mass, agitating,

adding oxygen and removin the heat of reaction to prevent the rise 0 temperature in the mass above 250 C.

8. The process of producing1 sodium monoxide consisting in mixing so ium and finely divided sodium monoxide in proportions to produce a mixture holding not over 10% uncombined metallic sodium, holding at a temperature between the melting 01111 of sodlum and 250 0., agitating an adding oxygen.

9. The. processof producing sodium monoxide consisting in mixing sodium and finely divided sod um monoxlde in proportions that do not produce a pasty mass, agitating, treating the mass with a mixture of-nitrogen and oxygen, and radiating the heat of reaction to prevent an elevation of temperature above 250 C.

10. The process of producin sodium monoxide consisting in mixing so um and finely divided sodium monoxldein proportions that do not produce a pasty mass, agitating, treatin the mass with a mixture ofnitrogen an not over 10% of oxygen at such a rate that the radiation of heat can prevent a rise of temperature in the mass above 250 C.

11. The process of producin sodium monoxide consisting in mixing so ium and finely divided sodlum monoxide in ro rtions to produce a pulverulent mass 01 in not over 10% of uncombined metallic sodium, holding at a temperature between the melting point of sodium and 250 C., agitating and subjecting the mass to a mixture of'mtrogen with not more than 10% of oxygen.

12. A product of manufacture consisting vided sodium and pulverulent sodium monin a pulverulent mixture comprising a fineoxide. ly divided alkali metal and a apulverulent 15. A product of manufacture comprising material inert to said alkali met an intimate pulverulent mixture of up to 5 13. A product of manufacture comprising about 10% finely divided sodium and about 15 an intimate ulverulent mixture of finely d1- 90% pulverulent sodium monoxide.

vided alkall metal and pulverulent alkali Signed at Perth Amboy, New Jersey, in metal monoxide. the county of Middlesex and State of New 14. A product of manufacture comprising J erse this 27th day of January, A. D. 1926. 1 an intimate pulverulent mixture of finely d1- 3 CTOR RUSSELL OARVETH. 

